1. Field of the Invention
The present invention relates to a new azo compound, a tautomer thereof and an azo dye, and in particular to a new azo compound, a tautomer thereof and an azo dye that are favorable in hue and superior in light fastness.
2. Description of the Related Art
Azo compounds have been used widely in various fields as dyes, because they absorb various visible lights different in wavelength, for example, as dyes for coloring synthetic resins, printing inks, sublimation-type heat-sensitive transfer materials, and inkjet-recording ink, and more recently, as functional dyes for use in the electronics field. Each azo compound has an absorption spectrum, which is a major property required for an azo compound as a dye. The hue of a dye exerts a significant influence on the hue, texture, and others of the material colored with the dye and a significant impact on visual impression. Accordingly the absorption spectra of dyes have long been studied, and reported in various literature (e.g., J. Fabian and H. Hartmann, “Light Absorption of Organic Colorants”, Springer-Verlag, Berlin, 1980).
The properties needed for a dye vary significantly according to the applications thereof. Dyes having a favorable hue and dyeing efficiency are desirable for dyeing sheepskin or cowhide, while dyes having a favorable hue and being less water-soluble and thus being resistant to washing are favorable for use in apparels. Thus in many cases, dyes should have multiple functions that meet the specific demands required for a desired application. In addition, there exists a strong need for dyes favorable in hue and light fastness under various conditions for use in printing ink, dyes for sublimation-type heat-sensitive recording materials, or inkjet-recording ink, and various diazo compounds or couplers have been disclosed for such purposes (e.g., Japanese Patent Application Laid-Open (JP-A) Nos. 4-59287 and 4-201483, and Mohr, J., J. Parkt. Chem., (2), 79, 1909, 47). However, although improvements have been made to some extent, there is still room for improvement in hue and light fastness.